OS MasterMap Water Network Layer is supplied as a single GeoPackage for the whole of Great Britain. GeoPackage (*.gpkg) is an open, non-proprietary, platform-independent, standards-based data format for geographic information systems (GIS), as defined by the Open Geospatial Consortium (OGC). It is designed to be a lightweight format that can contain large amounts of varied and complex data in a single, easy-to-distribute and ready-to-use file. GeoPackage is natively supported by numerous software applications.

GeoPackage offers users the following benefits:

• The single file is easy to transfer and offers the end-user a rich experience.

• Attribute names are not limited in length, making the format user-friendly.

• The file size limit is very large at 140 TB (A file size limit might be imposed by the file system to which the file is written).

• It supports raster, vector and database formats, making it a highly versatile solution.

• It is an OGC standard.

• In most cases, it is a plug-and-play format.

For information on how to open, use and understand a GeoPackage dataset, please refer to our ‘Getting Started with GeoPackage’ guide. Further detailed information on GeoPackage can be taken from the GeoPackage website.

Attribute naming differences between GML and GeoPackage formats

The naming of attributes between GeoPackage and the Geography Markup Language (GML) file is very similar as GeoPackage files are not limited in the number of characters for an attribute name. Therefore, the tables included here map the GML attribute name to the attribute name in the GeoPackage files.

The GML contains an attribute which describes the geometry of the feature; this is not applicable for a GeoPackage file as they are separated by their geometry.

Please note that the use of an asterisk symbol (*) in the following tables indicates that a particular attribute is not mapped to GML.